Electromagnetic connect/disconnect system for a vehicle

ABSTRACT

An electromagnetic connect/disconnect system with an electromagnet including a coil and a coil housing. The system also including a slide ring located between the coil housing and a sliding collar. The slide ring has a radially outer surface and a radially inner surface. The sliding collar has a first portion and a second portion. The first portion is located radially inward from the slide ring and defines a first set of axially extending teeth. The second portion is located radially inward from the first portion. A return spring groove is located radially inward from the sliding collar first portion and houses a return spring. An output gear is also included which has a second set of axially extending teeth for selective engagement with the first set of teeth.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.61/931,921 filed on Jan. 27, 2014, and U.S. Provisional Application No.62/025,192 filed on Jul. 16, 2014, which are incorporated by referencein their entirety herein.

FIELD OF THE INVENTION

An electromagnetic connect/disconnect system for a vehicle is described.More particularly, the device and the use of an electromagnet forengaging and disengaging driveline applications on a vehicle isdescribed.

BACKGROUND OF THE INVENTION

Typical connect/disconnect driveline systems for vehicles push torquethrough a torque coupling to the secondary axle to provide enhancementsin performance, handling and mobility. These systems require that thesecondary axle, and the rest of the driveline, be continually rotating,which reduces the overall efficiency of the vehicle, and reduces fueleconomy.

Secondary axle disconnects are available and they permit the secondaryaxle and prop shaft to stop rotating. These disconnect systems increasevehicle efficiency, but they can be slow to react. The systems typicallyuse an electric motor, gear reduction and a ball screw to compress aspring that will slide a collar to engage/disengage a shaft. Reactiontimes on the order of two seconds are common with these systems, whichis too long to be effective during most handling events.

The current systems also require power to both engage and disengage ashaft and/or remain engaged or disengaged. The latter situation mayrequire constant power to the system, which reduces overall systemefficiency. Of course, if power is lost, the system remains in its lastmode. In some applications, this is acceptable, but in otherapplications this is not preferred.

It would be desirable for a system to maintain vehicle efficiency, andto decrease reaction time to a level appropriate to deal with vehiclehandling events. It would also be desirable for a system toautomatically revert to a desired mode of operation in the event of apower failure.

SUMMARY

An electromagnetic connect/disconnect system with an electromagnetincluding a coil and a coil housing. The system also includes arotatable and axially slideable slide ring located between the coilhousing and a sliding collar. The slide ring has a radially outersurface and a radially inner surface. The sliding collar has a firstportion and a second portion. The first portion is located radiallyinward from the slide ring and defines a first set of axially extendingteeth. The second portion is located radially inward from the firstportion. A return spring groove is located radially inward from thesliding collar first portion and houses a return spring therein. Anoutput gear is also included which has a second set of axially extendingteeth for selective engagement with the sliding collar first set ofteeth.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a partial cut-away perspective view of an embodiment of thesystem;

FIG. 2 is a partial, schematic side view of the embodiment in FIG. 1 inone mode of operation;

FIG. 3 is a partial, schematic side view of the embodiment in FIG. 1 ina second mode of operation;

FIG. 4 is a partial, schematic side view of another embodiment of thesystem in one mode of operation;

FIG. 5 is a partial, schematic side view of the embodiment in FIG. 4 ina second mode of operation;

FIG. 6 is a partial, schematic side view of another embodiment of thesystem;

FIG. 7 is a partial, schematic side view of another embodiment of thesystem;

FIG. 8 is a partial, schematic side view of another embodiment of thesystem; and

FIG. 9 is a partial, schematic side view of another embodiment of thesystem.

PREFERRED EMBODIMENTS

It is to be understood that the invention may assume various alternativeorientations and step sequences, except where expressly specified to thecontrary. It is also to be understood that the specific assemblies,articles and features illustrated in the attached drawings, anddescribed in the following specification are simply exemplaryembodiments of the inventive concepts. Hence, specific dimensions,directions, or other physical characteristics relating to theembodiments disclosed are not to be considered as limiting, unlessexpressly stated otherwise. Also, although they may not be, likeelements in various embodiments may be commonly referred to with likereference numerals within this section of the application.

Turning now to FIG. 1, an electromagnetic connect/disconnect system 10is shown. The system 10 comprises an electromagnet 12 including a coil14 and coil housing 16. The coil housing 16 is hollow and encloses thecoil 14. The coil 14 comprises multiple wire windings within the coilhousing 16. The wire windings are connected to a source for electricity(not shown).

The coil housing 16 may be one piece or several pieces that have beenconnected together. As depicted in FIG. 2, the coil housing 16 is astationary, three piece housing. A first piece 18 of the coil housing 16has a generally U-shaped cross-section. The first piece of the housinghas three legs 20, 22, 24. The three legs 20, 22, 24 are unitary andone-piece with one another. Two legs 20, 22 of the first piece 18completely enclose two sides of the coil 14, with a first end 26 of oneleg 20 having a generally L-shaped cross-section cut out. A second piece28 of the coil housing 16 encloses a third side of the coil 14, and athird piece 30 of the coil housing 16 encloses the final side of thecoil 14.

The second piece 28 of the coil housing 16 has a first portion 32 and asecond portion 34. The first and second portions 32, 34 are unitary andone-piece with one another. The first portion 32 is thicker than thesecond portion 34 and is located between a sliding ring 36 and the coil14. The second portion 34 is located between a leg 24 of the first piece18 of the coil housing 16 and the coil 14.

The third piece 30 of the coil housing 16 has a generally rectangularcross-section and has a first end 38 and a second end 40. The first end38 abuts the L-shaped first end 26 of a leg 20 of the first piece 18 ofthe coil housing 16. The second end 40 of the third piece 30 has aninwardly extending protrusion 42 that is adjacent an outside end of thefirst portion 32 of the second piece 28 of the coil housing 16. Thethree housing pieces together 18, 28, 30 substantially enclose the coil14.

The slide ring 36 is located between the first 18 and second 28 piecesof the coil housing 16 and a sliding collar 44. More particularly, theslide ring 36 is located radially inward from the coil housing 16 and isin direct contact therewith. The slide ring 36 is constructed of ametallic material that is susceptible to magnetic forces, such as steel.

The slide ring 36 has a radially outer surface 46, a radially innersurface 48, a first end 50 and a second end 52. The outer surface 46 isin direct contact with the first and second pieces 18, 28 of the coilhousing 16. The slide ring 36 has a complementary shape to the secondpiece 28 of the coil housing 16. More particularly, the second end 52 ofthe slide ring 36 may be slightly L-shaped to match a complementaryL-shape on a side of the second piece 28 of the coil housing 16.

An arm 54 extends radially inward from the inner surface 48 of the slidering 36. A first side 56 of the inwardly extending arm 54 is locatedaxially adjacent a first bushing 58. A second side 60 of the inwardlyextending arm 54 is adjacent the sliding collar 44. The slide ring 36 isadapted for selective axial movement.

The first bushing 58 is located between the slide ring 36 and thesliding collar 44. The first bushing 58 is a continuous, ring-shapedstructure that has a first end 62, a second end 64, an inner surface 66and an outer surface 68. The first end 62 of the bushing 58 is adjacentthe inner surface 48 of the slide ring 36. The second end 64 of thebushing 58 is in direct axial contact with the sliding collar 44. Theinner surface 66 of the bushing 58 is in direct radial contact with thesliding collar 44, and the outer surface 68 of the bushing 58 is indirect radial contact with the first side 56 of the inwardly extendingarm 54 of the slide ring 36. The first bushing 58 is constructed of anon-magnetic material, such as, but not limited to, plastic.

The sliding collar 44 is located directly radially inward from the slidering 36 and directly radially outward from an output shaft 74, and has afirst portion 70 and a second portion 72. The first and second portions70, 72 are unitary and one-piece with one another. More particularly,the first portion 70 is located directly radially inward from the slidering 36 and extends radially outward parallel to the radially inwardlyextending arm 54 of the slide ring 36. An inner surface 76 of the firstportion 70 of the sliding collar 44 has a first set of axially extendingteeth 78.

The second portion 72 is located radially inward from the first portion70, and extends in an outward direction parallel with the output shaft74. The second portion 72 defines a first set of axially extendingsplines 86. The splines 86 are integrally formed and unitary with thesliding collar 44 and allow for axial movement along the output shaft74.

A return spring groove 88 as also depicted in FIGS. 1 and 2, is locatedradially inward from the first portion 70 of the sliding collar 44. Thereturn spring groove 88 receives a return spring 90 therein. A first end92 of the return spring 90 abuts an end of the return spring groove 88.A second end 94 of the return spring 90 abuts a snap ring 96.

The snap ring 96 is located in a snap ring groove 98 that extends intothe output shaft 74 and an output gear 82. The snap ring 96 provides astop for the return spring 90.

The output gear 82 is located radially inward from the slide ring 36 andradially outward from the output shaft 74. An outer surface 84 of theoutput gear 82 defines a second set of axially extending teeth 102 forengaging the first set of axially extending teeth 78 on the slidingcollar 44. The engagement of the teeth sets 78, 102 rotationally locksthe sliding collar 44 with the output gear 82.

A second bushing 104 is a continuous, ring-shaped structure and has afirst end 106, a second end 108, an inner surface 110 and an outersurface 112. The second end 108 and the inner surface 110 of the secondbushing 104 are both in direct contact with the outer surface 84 of theoutput gear 82. The outer surface 112 of the second bushing 104 abuts asecond snap ring 114. The second bushing 104 is constructed of anon-magnetic material, such as, but not limited to, plastic. The secondsnap ring 114 is housed within a second snap ring groove 116 located onthe radially outer surface 84 of the output gear 82.

A bearing 118 is located on an inner surface 120 of the output gear 82,and allows for rotation of the output shaft 74 within the output gear82.

The system has two modes of operation. In a first mode of operation asdepicted in FIG. 2, the sliding collar 44 and the output gear 82 are notconnected or rotating together, but it is desired that they be connectedso that they rotate together. When this mode is to be used, electricityis sent to the coil 14. The coiled wires create a magnetic flux. Withina few milliseconds of the coil 14 being energized, the magnetic fluxcontributes to the magnetic slide ring 36 moving in the axial direction.The slide ring 36 axially moves the first bushing 58, which in turnaxially moves the sliding collar 44, pushing the sliding collar 44 intoengagement with the output gear 82.

As the first mode is being engaged, the first set of teeth 78 on thesliding collar 44 are not engaged with the second set of teeth 102 onthe output gear 82; a gap separates the two sets of teeth 78, 102.However, as the sliding collar 44 is moved, the gap separating the twosets of teeth 78, 102 closes. In a short amount of time, on the order ofmilliseconds, the gap is closed and the first set of teeth 78 on thesliding collar 44 engage with the second set of teeth 102 on the outputgear 82. Upon engagement of the two sets of teeth 78, 102, the slidingcollar 44 is rotationally fixed to the output gear 82, as depicted inFIG. 3. The rotation from the sliding collar 44 is transferred throughthe output gear 82 to the output shaft 74.

When it is desired that the components no longer be engaged, theelectricity to the coil 14 is interrupted. The return spring 90 pushesagainst the sliding collar 44 thus urging it axially away from theoutput gear 82. The biasing of the return spring 90 separates the twosets of teeth 78, 102. The return spring 90 permits the system 10 todefault to a position where the components are not engaged. When thesliding collar 44 is not engaged with the output gear 82, the system 10is in the second mode as depicted in FIG. 2.

In another embodiment as depicted in FIGS. 4 and 5, the coil housing 236is a stationary, two piece housing. A first piece 240 of the coilhousing 236 has a generally J-shaped cross-section and the second piece242 of the coil housing 236 has a generally L-shaped cross-section. Thelegs 244, 246 of the J-shaped housing 240 face the L-shaped housing 242and a leg 248 of the L-shaped housing 242 faces the J-shaped housing 240to substantially enclose the coil 234.

The J-shaped coil housing 240 is located directly radially inward from acover housing 230 and contacts the cover housing 230. The coil housing240 is located radially outward from the axle output shaft 202. Moreparticularly, the coil housing 240 is located radially outward from anaxially extending wall outer surface 218. A radial distance 250separates the coil housing 236 from the axially extending wall outersurface 218.

A slide ring 252 is located between the coil housing 236 and the axiallyextending wall outer surface 218. More particularly, the slide ring 252is located radially inward from the coil housing 236 and is in directcontact therewith.

The slide ring 252 has an outer surface 254, an inner surface 256, afirst end 258 and a second end 260. The outer surface 254 is in directcontact with the first piece coil housing 240. The slide ring 252 has acomplementary shape to the second piece coil housing 242. Moreparticularly, the second end 260 of the slide ring 252 may be tapered tomatch a complementary tapered surface 262 on the second piece coilhousing 242.

The inner surface 256 faces the axially extending wall outer surface218. The axle output shaft 202 extends through the inner surface 256 ofthe slide ring 252. The first end 258 of the slide ring 252 is locatedaxially adjacent a bearing 226. The slide ring 252 can rotate with theaxle output shaft 202. The slide ring 252 is also adapted for selectiveaxial movement. The slide ring 252 is axially adjacent a bushing 264.

The bushing 264 is a continuous, ring-shaped structure and it has thefirst end 266, a second end 268, an inner surface 270 and an outersurface 272. The first end 266 of the bushing 264 is in direct axialcontact with the second end 260 of the slide ring 252. The second end268 of the bushing 264 is located in direct axial contact with a slidingcollar 274. The inner surface 270 of the bushing 264 is in direct radialcontact with the sliding collar 274. The bushing 264 entirely encirclesthe sliding collar 274. The outer surface 272 of the bushing 264 islocated directly radially inward from the L-shaped housing 242. Thebushing 264 is constructed of a non-magnetic material, such as, but notlimited to, plastic.

The bushing 264 can rotate with the axle output shaft 202, or thebushing 264 can be secured to prevent its rotation with the axle outputshaft 202. It may be desirable to secure the bushing 264 to preventrotation with the axle output shaft 202 if it interferes with thesystem, described below. In the depicted embodiment, the bushing 264 canrotate with the axle output shaft 202.

The sliding collar 274 has a first portion 276 and a second portion 278.The first and second portions 276, 278 are unitary and one-piece withone another. The first portion 276 is located directly radially inwardfrom the slide ring 236 and directly radially outward from the axleoutput shaft 202. The first portion 276 of the sliding collar 274axially slides within the inner surface 256 defined by the slide ring252.

An inner surface 280 of the first portion 276 has a first set of axiallyextending splines 282. The first set of axially extending splines 282are engaged with a second set of axially extending splines 284 locatedon the outer surface 218 of the axially extending wall 216 of the axleoutput shaft 202. The engagement of the splines 282, 284 rotationallylocks the sliding collar 274 with the axle output shaft 202 but permitsthe sliding collar 274 to selectively move axially along the axle outputshaft 202.

The second portion 278 of the sliding collar 274 extends in an outwardradial direction away from the axle output shaft 202. The second portion278 defines a first set of axially extending teeth 286. The teeth 286are integrally formed and unitary with the sliding collar 274.

A return spring groove 288 is located radially inward in the secondportion 278, adjacent the axle output shaft 202. The return springgroove 288 receives a return spring 290 therein. A first end 292 of thespring 290 abuts an end of the groove 288. A second end 294 of thespring 290 abuts a snap ring 296.

The snap ring 296 is also located in a second snap ring groove 300 thatextends into the axle output shaft 202. The snap ring 296 retains thesliding collar 294 by providing a stop for the spring 290.

A shaft 302 is selectively connected with the axle output shaft 202 forrotation therewith. The shaft 302 has a first male end portion 304 thatis located within the hollow interior 214 of the axle output shaft 202.A sleeve 306 may be located between the hollow interior 214 of the axleoutput shaft 202 and the male portion 304 of the shaft 302. The sleeve306 facilitates rotation between the two shafts 202, 302 when they arenot rotating with one another.

The shaft 302 has a first increased diameter portion 308 that is unitarywith the male end portion 304 and axially directly adjacent the male endportion 304. An outer surface 310 of the increased diameter portion 308has a set of axially extending splines 312, and a radial groove 314extending through the spline set 312.

An output gear 316 is located radially outward from the increaseddiameter portion 308 of the shaft 302. More particularly, an innerradial surface 318 of the output gear 316 defines a set of splines 320meshed with the shaft splines 312. The splines 312, 320 rotationally fixthe output gear 316 to the shaft 302. A second set of radially extendingteeth 322 extend along a side surface 324 of the output gear 316.

A groove 326 radially extends into the output gear splines 320. A snapring 328 is located in the output gear groove 326 and the shaft groove314 to axially fix the output gear 316 and the shaft 302.

An inner race 330 of a bearing 332 is located on an outer surface 334 ofthe output gear 316. An outer race 336 of the bearing 332 is located indirect contact with the housing 230. The bearing 332 facilitatesrotation of the output gear 316 with respect to the stationary housing230.

The system has two modes of operation. In a first mode of operation asdepicted in FIG. 4, the sliding collar 274 and the output gear 316 arenot connected or rotating together, but it is desired that they beconnected so that they rotate together. When this mode is to be used,electricity is sent to the coil 234. The coiled wires create a magneticflux. Within a few milliseconds of the coil 234 being energized, themagnetic flux contributes to the magnetic slide ring 252 moving in theaxial direction. The slide ring 252 axially moves the bushing 264, whichin turn axially moves the sliding collar 274, pushing the sliding collar274 into output gear 316.

As the first mode is being engaged, the first set of teeth 286 on thesliding collar 274 teeth are not engaged with the second set of teeth322 on the output gear 316; a gap separates the two sets of teeth 286,322. However, as the sliding collar 274 is moved, the gap separating thetwo sets of teeth 286, 322 closes. In a short amount of time, on theorder of milliseconds, the gap is closed and the first set of teeth 286on the sliding collar 274 engage with the second set of teeth 322 on theoutput gear 316. Upon engagement of the two sets of teeth 286, 322, thesliding collar 274 is rotationally fixed to the output gear 316, asdepicted in FIG. 5. The rotation from the sliding collar 274 istransferred through the output gear 316 to the shaft 302.

When it is desired that the components no longer be engaged, theelectricity to the coil 234 is interrupted. The return spring 290 pushesagainst the sliding collar 274 thus urging it axially away from theoutput gear 316. The biasing of the return spring 290 separates the twosets of teeth 286, 322. The return spring 290 permits the system 210 todefault to a position where the components are not engaged. When thesliding collar 274 is not engaged with the output gear 316, the system210 is in the second mode as depicted in FIG. 4.

In another embodiment the systems 10, 210 described above may include apermanent magnet 138, 338, as depicted in FIGS. 6 and 7. The permanentmagnetic flux of the magnet 138, 338 adds to the flux generated by theenergized coil 14, 234. Furthermore, the current in the coil 14, 234causes the coil housing 16, 240 to become magnetized. The sum of thepermanent magnetic flux, the coil flux, and the housing magnetism isgreater than the sum of the return spring 90, 290 force and frictionforce of the slide ring 36, 252, which causes the slide ring 36, 252 tomove.

As the first mode is being engaged, the first set of teeth 78, 286 ofthe sliding collar 44, 274 are not engaged with the second set of teeth102, 322 on the output gear 82, 316; a gap separates the two sets ofteeth 78,286; 102, 322. However, as the sliding collar 44, 274 is moved,the gap separating the two sets of teeth 78, 286; 102, 322 closes. In ashort amount of time, on the order of milliseconds, the gap is closedand the first set of teeth 78, 286 of the sliding collar 44, 274 engagewith the second set of teeth 102, 322 on the output gear 82, 316. Uponengagement of the two sets of teeth 78, 286; 102, 322, the slidingcollar 44, 274 is rotationally fixed to the output gear 82, 316.

The permanent flux from the magnet 138, 338 and/or coil housing 16, 240is strong enough to hold the first set of teeth 78, 286 of the slidingcollar 44, 274 in engagement with second set of teeth 102, 322 on theoutput gear 82, 316. Therefore, if power is lost to the coil 14, 234,the output shaft 74, 202 will stay in the engaged position.Additionally, the system 10, 210 does not require power to stay in theengaged position. This is advantageous since it can operate in theengaged position without continuing to draw electrical power, whichmakes the system more efficient.

When it is desired that the component no longer be engaged, a current isprovided to the coil 14, 234 to create a flux in the opposite direction.The flux would cancel the flux from the permanent magnet 138, 338 and/ordemagnetize the coil housing 16, 240. The return spring 90, 290 pushesagainst the sliding collar 44, 274 thus urging it axially away from theoutput gear 82, 316. The biasing of the return spring 90, 290 separatesthe two sets of teeth 78, 286; 102, 322. When the sliding collar 44, 274is not engaged with the output gear 82, 316, the system 10, 210 is inthe second mode.

The system does not require power to stay in the disengaged position.This is advantageous since it can operate in the disengaged positionwithout continuing to draw electrical power, which makes the system moreefficient.

It can be appreciated that one embodiment of the system described anddepicted herein is for an axle connect/disconnect system. However, thedevice described herein is not limited to just axles. Instead, thedevice can be applied to other devices, equipment and methods including,but not limited to, power take off units.

FIG. 8 depicts one embodiment of a power take off unit utilizing thesystem described herein. Provided is a coil housing 436 housing apermanent magnet 538 therein. Radially inboard of the housing 436 is aslide ring 452. Radially inboard of the slide ring 452 is a slidingcollar 474. The sliding collar 474 has teeth 486 on one end portion. Theother end portion of the sliding collar 474 has splines 482 that engagewith shaft splines. The teeth 486 are complimentary to and selectivelyengage teeth 522 on an output gear 516. The output gear 516 is mountedon a bearing 532 to permit the gear 516 to rotate with respect to ahousing. The power take off unit functions in the same way as the axlesystem described above.

FIG. 9 depicts another embodiment of a power take off unit alsoutilizing the system described herein. Provided is a coil housing 636housing a permanent magnet 638 therein. Radially inboard of the housing636 is a slide ring 652. Radially inboard of the slide ring 652 is asliding collar 674. The sliding collar 674 has teeth 686 on one endportion. The other end portion of the sliding collar 674 has splines 682that engage with shaft splines. The teeth 686 are complimentary to andselectively engage teeth 722 on an output gear 716. A return spring 690pushes against the sliding collar 674 urging it away from the outputgear 716. The power take off unit functions in the same way as the axlesystem described above.

From the foregoing detailed description, it will be apparent thatvarious modifications, additions, and other alternative embodiments arepossible without departing from the true scope and spirit. Theembodiments discussed herein were chosen and described to provide thebest illustration of the principles of the invention and its practicalapplication to thereby enable one of ordinary skill in the art to usethe invention in various embodiments and with various modifications asare suited to the particular use contemplated. As should be appreciated,all such modifications and variations are within the scope of theinvention.

What is claimed is:
 1. An electromagnetic connect/disconnect system,comprising: an electromagnet comprising a coil and a coil housing; arotatable and axially slidable slide ring located between said coilhousing and a sliding collar, said slide ring comprising a radiallyouter surface, a radially inner surface, a first end and a second end;said sliding collar comprising a first portion and a second portion,said first portion is located directly radially inward from said slidering, said first portion defining a first set of axially extendingteeth, said second portion is located radially inward from said firstportion; a return spring groove located radially inward from saidsliding collar first portion and housing a return spring therein; and anoutput gear comprising a second set of axially extending teeth forselective engagement with said sliding collar first set of teeth.
 2. Anelectromagnetic connect/disconnect system according to claim 1, whereinsaid coil housing is a three piece housing.
 3. An electromagneticconnect/disconnect system according to claim 2, wherein one piece ofsaid coil housing is a U-shaped cross-section.
 4. An electromagneticconnect/disconnect system according to claim 2, wherein one piece ofsaid coil housing comprises a first portion and a second portion andsaid first portion is thicker than said second portion.
 5. Anelectromagnetic connect/disconnect system according to claim 1, whereinsaid second end of said slide ring is L-shaped to match a complementaryL-shape on a side of said coil housing.
 6. An electromagneticconnect/disconnect system according to claim 1, wherein an arm extendsradially inward from said radially inner surface of said slide ring andsaid first portion of said sliding collar extends radially outwardparallel to said slide ring radially inwardly extending arm.
 7. Anelectromagnetic connect/disconnect system according to claim 1, whereina bushing is located between said slide ring and said sliding collar. 8.An electromagnetic connect/disconnect system according to claim 1,wherein said output gear is located radially inward from said slide ringand radially outward from an output shaft.
 9. An electromagneticconnect/disconnect system according to claim 1, wherein said coilhousing is a two piece housing.
 10. An electromagneticconnect/disconnect system according to claim 9, wherein one piece ofsaid coil housing is a J-shaped cross-section.
 11. An electromagneticconnect/disconnect system according to claim 9, wherein one piece ofsaid coil housing is a L-shaped cross-section.
 12. An electromagneticconnect/disconnect system according to claim 9, wherein a slide ring hasa complementary shape to one piece of said coil housing.
 13. Anelectromagnetic connect/disconnect system according to claim 1, whereinsaid electromagnet comprises a permanent magnet.